Such emergency oxygen devices are used to supply oxygen to passenger of an aircraft in an emergency situation like a decompression situation or smoke or the like on board of an aircraft. Usually, two or three oxygen masks are stored above the passenger in a ceiling compartment, e.g. a separate casing, and in case of an emergency are released to fall out of the casing. The oxygen masks then are provided to the passenger at a certain level defined by means to connect the oxygen masks in the dropped state relative to the casing, the oxygen generator or any other fixed point above the passenger.
The oxygen source may preferably be a chemical oxygen generator. A chemical oxygen generator comprises one or more substances which are able to conduct a chemical reaction producing oxygen. This chemical reaction must be started in an emergency situation to provide said oxygen to the passenger. It is known to initiate said chemical reaction by a starter unit which is activated by a mechanical pulling force exerted by the passenger via the oxygen mask. The starter unit then includes means for a short exothermic reaction sufficient to initiate the chemical reaction which thereafter is conducted as exothermic, self-sustaining reaction.
The oxygen source may comprise oxygen as a gaseous, liquid or solid state in a pure condition or as a mixture. The oxygen source may be a pressure tank or may be an On-Board-Oxygen-Generating System (OBOGS), generating oxygen from bleed air out of a compressor stage or out of ambient air outside or inside the cabin of the aircraft. Still further, the oxygen source may provide oxygen by way of an electrolytic process, a membrane diffusion process or by gravitational separation, in particular in a centrifuge. The activator unit is adapted to initiate oxygen supply from the specific type of oxygen source. The activator unit may e.g. be a valve controlling the flow out of an oxygen pressure tank.
For exerting said pulling force it is known to provide a lanyard arrangement from said oxygen mask to the activation unit. A general problem associated with such an arrangement is the need to provide a safe and reliable transfer of the pulling force by at the same time offering the oxygen mask to the passenger at a predetermined level which is easily reached by any passenger from children to adults. Further, such lanyard must ensure that the oxygen mask can be pulled down towards the passenger and worn by the passenger in a convenient way. Usually, these requirements are fulfilled by a significant length of the lanyard which however bears the risk that the lanyard entangles and thus produces loops, slings or meshes or even is fixed by joins inside the casing. This may result in the oxygen mask not being properly presented to the passenger or the passenger not being able to pull the mask towards his mouth and nose and to breathe oxygen.
The risk of such entanglement of the lanyards even increases if more than one oxygen mask with corresponding lanyards and oxygen flow tubes are provided inside one casing and are supplied from one chemical oxygen generator. Usually, in order to save costs and weight, emergency oxygen devices include two, three or even more oxygen masks in one casing and these oxygen masks are provided from one single chemical oxygen generator. In such case, however, it is required that the oxygen generator can be started by each of said oxygen masks via a pulling force or the like. The need for lanyards for each of the oxygen masks and the storage of said lanyards inside the casing in the non-emergency situation bears the significant risk that entanglements occur and hinder a proper function or dropping out of the oxygen masks.